SCR脱硝装置中整流格栅的优化设计

基于CFD模拟软件对某选择性催化还原(SCR)脱硝装置进行数值模拟,分析了不同整流格栅间距、形式对反应器上部流场的影响。以不同高度截面的烟气速度变异系数CV和最大烟气入射角为定量评价指标,给出了满足性能要求的整流格栅设计参数范围以及最优设计方案。     

螺旋升流反应器氧传递性能的试验研究

本文主要针对螺旋升流反应器技术特性，对工艺的好氧反应器进行了氧传递性能的试验研究，考察了反应器水深、曝气量等对螺旋升流反应器氧转移过程的影响；并对试验数据进行回归，得到了氧传质总系数与螺旋升流反应器内表现气速的数学关系。试验结果表明，螺旋升流反应器具有良好的氧传递特性，是一种新型的高效、节能的污水处理反应技术。     

除尘器入口烟道流场流动力学数值模拟技术

结合燃煤电厂电袋复合除尘器的入口烟道气流分布的工程案例,采用计算流体动力学（简称CFD）数值模拟技术,对烟道内的速度场进行三维数值模拟;根据分析结果进行烟道的导流板的设置,改善烟道的流场,并使入口烟道的各分支烟道流量分配均匀。对比现场烟道流量分配的测试结果,验证了CFD模拟计算的准确性。     

旋转压缩机油路系统仿真与试验研究

压缩机泵油系统对滚动转子压缩机性能和可靠性非常重要.为了了解压缩机泵油特性.本文应用CFD软件,采用VOF模型对滚动转子压缩机整个泵油系统进行数值模拟,搭建试验台进行试验,并将模拟和试验结果进行对比,结果表明上法兰螺旋槽处润滑油流量结果吻合很好,误差在10％以内,证明了该仿真方法的可行性.     

袋式除尘器气流组织的数值模拟分析

文章通过采用流体动力学CFD软件对袋式除尘器中单元模块的除尘空间气流组织进行数值模拟分析，给出了不同位置的布袋不同高度上的气流速度图，将模拟结果与实际工程运行情况进行对比，分析了其可靠性，为袋式除尘器的改进和设计提供了理论依据。     

石灰法制浆黑液厌氧发酵技术的研究—厌氧发酵动态模型实验

本文介绍了应用上流式厌氧污泥床反应器处理半化学浆石灰法制浆黑液的研究.所采用的反应器容积为21升,当进水COD负荷荷为1.6克/升·天至7.0克/升·天时,处理后、COD去除率为70—74.5％(BOD去除率为80～88％).其沼气产气率0.4～0.7升/克COD(0.6～0.7升/克BOD),甲烷含量60～65％,滞留期1.5～1.6天.经过较长时间的稳定运行,厌氧活性污泥达到颗粒化程度,结果证明实验是成功的. 本实验为治理同类型制浆黑液的污染提供了一种有效的方法.并且是一种可获取能源的低能耗的实用性技术.     

石灰法制浆黑液厌氧发酵技术的研究——厌氧发酵动态模型实验

本文介绍了应用上流式厌氧污泥床反应器处理半化学浆石灰法制浆黑液的研究.所采用的反应器容积为21升,当进水 COD 负荷荷为1.6克/升·天至7.0克/升·天时,处理后、COD 去除率为70—74.5%(BOD 去除率为80～88%),其沼气产气率0.4～0.7升/克 COD(0.6～0.7升/克 BOD),甲烷含量60～65%,滞留期1.5～1.6天。经过较长时间的稳定运行,厌氧活性污泥达到颗粒化程度,结果证明实验是成功的.本实验为治理同类型制浆黑液的污染提供了一种有效的方法.并且是一种可获取能源的低能耗的实用性技术.     

使用厌氧混合消化反应器处理石化废水

本文介绍一种采用厌氧混合消化反应器对酸性石化废水进行厌氧处理的方法。该法在HRT(水力停留时间,以下类同)为17小时、有机负荷率为20.04(公斤.化学耗氧量/立方米.天的条件下,可获得挥发性有机酸去除率为91％,化学耗氧量去除率为84％。反应器最终出水含氨氮为44毫克/升、含磷酸盐12.3毫克/升。     

挥发性油藏回注气井控因素分析及措施

文章明确了挥发性油藏天然气回注井控的安全环保关键因素;量化了低渗挥发性油藏天然气回注注入能力,确定注入端各节点安全生产压力分布,攻关相关配套工艺设备,实现安全有效注入;开展室内实验和PVT相态拟合,分析注天然气后天然气和原油性质变化规律,创新非混相驱组分数值模拟参数优化方法,开展带人工压裂裂缝的组分数值模拟,精准确定压力场分布,降低计量及监测不准带来的安全隐患;明确注气井气窜影响因素,优化注采参数,抑制油井气窜,降低生产风险,实现井控安全情况下的天然气驱环保高效开发。     

煤粉锅炉SCR脱硝系统的设计与优化

以某新建460t/h煤粉炉的SCR脱硝项目为例,基于CFD软件完成几何建模、网格划分、数值计算等模拟工作,分析SCR脱硝系统的速度分布、NH3浓度分布、烟气入射角及压损情况。结果显示:最终的导流板布置方案能达到比较理想的流场分布,脱硝系统满足各项性能指标要求。     

Numerical simulation of chemical looping combustion process with CaSO4 oxygen carrier

Chemical-looping combustion (CLC) is a promising technology for the combustion of gas or solid fuel with efficient use of energy and inherent separation of CO₂. The technique involves the use of an oxygen carrier which transfers oxygen from combustion air to the fuel, and hence a direct contact between air and fuel is avoided. A chemical-looping combustion system consists of a fuel reactor and an air reactor. A metal oxide is used as oxygen carrier that circulates between the two reactors. The air reactor is a high velocity fluidized bed where the oxygen carrier particles are transported together with the air stream to the top of the air reactor, where they are then transferred to the fuel reactor using a cyclone. The fuel reactor is a bubbling fluidized bed reactor where oxygen carrier particles react with hydrocarbon fuel and get reduced. The reduced oxygen carrier particles are transported back to the air reactor where they react with oxygen in the air and are oxidized back to metal oxide. The exhaust from the fuel reactor mainly consists of CO₂ and water vapor. After condensation of the water in the exit gas from the fuel reactor, the remaining CO₂ gas is compressed and cooled to yield liquid CO₂, which can be disposed of in various ways.With the improvement of numerical methods and more advanced hardware technology, the time needed to run CFD (Computational fluid dynamics) codes is decreasing. Hence multiphase CFD-based models for dealing with complex gas-solid hydrodynamics and chemical reactions are becoming more accessible. Until now there were a few literatures about mathematical modeling of chemical-looping combustion using CFD approach. In this work, the reaction kinetics model of the fuel reactor (CaSO₄ + H₂) was developed by means of the commercial code FLUENT. The bubble formation and the relation between bubble formation and molar fraction of products in gas phase were well captured by CFD simulation. Computational results from the simulation also showed low fuel conversion rate. The conversion of H₂ was about 34% partially due to fast, large bubbles rising through the reactor, low bed temperature and large particles diameter.     

雷达关键部件对西北地区典型环境适应性的综合仿真研究

长期工作在西北地区大温差、多风砂和强紫外线等恶劣复杂环境下的雷达装备表面极易出现表面磨蚀或损坏。建立了雷达对西北地区综合环境适应性的仿真分析方法,以计算流体动力学(CFD)软件FLUENT为平台,对雷达典型部件在大温差、多风砂和强紫外线环境中的表面状态进行仿真模拟。仿真结果与雷达装备实际情况较为吻合,为进一步深入研究相关物理机理以及设计防护措施提供了理论依据。     

Large eddy simulation of oxy-coal combustion in an industrial combustion test facility

Oxy-fuel combustion is considered as one of the most promising technologies for carbon capture and storage (CCS). In this study, a commercial computational fluid dynamics (CFD) code has been employed for the simulation of an air-fired coal combustion and an oxy-fired coal combustion with recycled flue gas in a 1 MW_th combustion test facility. Reynolds–averaged Navier–Stokes (RANS) solutions have been obtained for both cases. Results indicate that the CFD code with existing physical sub-models can provide a reasonable prediction for the air-fired combustion. However, the prediction for the oxy-fired case has not been as satisfactory as expected. In order to assess the impact of the turbulence treatment in CFD on the predictions, large eddy simulation (LES) has been performed for oxy-fired case and compared with the results from the RANS simulation and the available experimental data. Although the results suggest that LES can provide a more realistic prediction of the shape and the physical properties of the flame, there has not been significant improvement in the prediction of the temperature. In addition, the complexity of the problem requires more detailed experimental data for the validation of the LES. In order to improve the validity of numerical simulations for design purposes, further modelling improvements for oxy-coal combustion that are necessary for more accurate predictions are addressed. Based on this study, it is envisaged that the complexity in the oxy-coal combustion process requires more detailed analyses of the available physical sub-models.     

Artificially roughened solar air heater: A comparative study

Artificially roughened solar air heater has been topic in research for the last 30 years. Prediction of heat transfer and fluid flow processes of an artificially roughened solar air heater can be obtained by three approaches: theoretical, experimental, and computational fluid dynamics (CFD). This article provides a comprehensive review of the published literature on the investigations of artificially roughened solar air heater. In the present article, an attempt has been made to present holistic view of various roughness geometries used for creating artificial roughness in solar air heater for heat transfer enhancement. This extensive review reveals that quite a lot of work has been reported on design of artificially roughened solar air heater by experimental approach but only a few studies have been done by theoretical and CFD approaches. Finally this article presents a comparative study of thermo-hydraulic performance of 21 different types of artificial roughness geometries attached on the absorber plate of solar air heater in terms of thermo-hydraulic performance parameter. Heat transfer and friction factor correlations developed by various investigators for different types of artificially roughened solar air heaters have also been reported in this article.     

CFD技术在海洋平台可燃气体泄漏模拟中的应用

计算流体动力学(CFD)技术可以实现分析、判断和预测天然气泄漏后所影响到的扩散区域,对事故的预防、控制以及平台应急、逃生方面具有指导意义。文章介绍了CFD方法以及可燃气体泄漏的相关理论,并对海洋平台可燃气体泄漏进行模拟分析,研究结果可为泄漏现场人员疏散和安全技术管理提供有效依据。     

Investigation of activated carbon/ethanol for low temperature adsorption cooling

Commercially available adsorption cooling systems use water/silica gel, water/zeolite and ammonia/ chloride salts working pairs. The water-based pairs are limited to work above 0°C due to the water high freezing temperature, while ammonia has the disadvantage of being toxic. Ethanol is a promising refrigerant due to its low freezing point (161 K), nontoxicity, zero ozone depletion, and low global warming potential. Activated carbon (AC) is a porous material with high degree of porosity (500–3000 m²/g) that has been used in wide range of applications. Using Dynamic Vapour Sorption (DVS) test facility, this work characterizes the ethanol adsorption of eleven commercially available activated carbon materials for cooling at low temperature of ?15°C. DVS adsorption results show that Maxsorb has the best performance in terms of ethanol uptake and adsorption kinetics compared to the other tested materials. The Maxsorb/ethanol adsorption process has been numerically modeled using computational fluid dynamics (CFD) and simulation results are validated using the DVS experimental measurements. The validated CFD simulation of the adsorption process is used to predict the effects of adsorbent layer thickness and packing density on cycle uptake for evaporating temperature of ?15°C. Simulation results show that as the thickness of the Maxsorb adsorbent layer increases, its uptake decreases. As for the packing density, the amount of ethanol adsorbed per plate increases with the packing density reaching maximum at 750 kg/m³. This work shows the potential of using Maxsorb/ethanol in producing low temperature cooling down to ?15°C with specific cooling energy reaching 400 kJ/kg.     

Dynamic contact angle effects on gas-liquid behaviors in the cathode of proton exchange membrane fuel cell with stirred tank reactor design

Liquid water management is still a critical issue in the improvement of proton exchange membrane fuel cell (PEMFC) performance. In this work, for the first time, the liquid water behavior and transport inside the cathode of a PEMFC with a stirred tank reactor (STR) design, rather than the conventional PEMFC flow channel design, are numerically studied. The dynamic contact angle (DCA) is applied to multiple wall boundaries in the numerical model through a user-defined-function (UDF) code, i.e., STR-DCA model. Another numerical model with the static contact angle (SCA) and same operating conditions, i.e., STR-SCA model, is also developed for comparison. The volume of fluid (VOF) method is employed in the simulation to track the gas-liquid interface. The results show that the liquid water distribution and transport are significantly different between these two models, indicating the remarkable effects of DCA on the simulation results. It is also verified the capability of STR-PEMFC to reduce the liquid water flooding, showing the potential of this channel-less type fuel cell in the further development.